Rotational ultrasound imaging catheter with extended catheter body telescope

ABSTRACT

The present invention generally relates to devices for imaging the interior of a vessel. The device can involve an elongated body configured to fit within the lumen of a vessel, a rotatable shaft positioned inside the elongated body, and a telescoping element, wherein a portion of the elongated body extends through the telescoping element, in which the elongated body is configured to contain the rotatable shaft inside the telescoping element.

RELATED APPLICATION

This application claims the benefit of and priority to U.S. ProvisionalSer. No. 61/745,285, filed Dec. 21, 2012, which is incorporated byreference in its entirety.

FIELD OF THE INVENTION

The present invention generally relates to a rotational imaging devicefor imaging the interior of a vessel.

BACKGROUND

Intravascular ultrasound (IVUS) is an important interventionaldiagnostic procedure for imaging atherosclerosis and other vesseldiseases and defects. The procedure involves the threading of an IVUScatheter over a guidewire into a blood vessel and the acquisition ofimages of the surrounding area using ultrasonic echoes. Thethree-dimensional images obtained via IVUS are often more informativethan images derived from other imaging techniques, such as angiography,which provide only two dimensional images.

Conventional IVUS catheters come in various designs, including includemechanical or rotational IVUS catheters. In a rotational IVUS catheter,a single transducer having a piezoelectric crystal is rapidly rotatedwhile the transducer is intermittently excited with an electrical pulse.The excitation pulse causes the transducer to vibrate, sending out aseries of transmit pulses. The transmit pulses are emitted at afrequency that allows time for receipt of echo signals. The sequencesignals interspersed with receipt signals provides the ultrasound datarequired to reconstruct a complete cross-sectional image of a vessel.

Conventional rotational IVUS catheters include a drive cable disposedwithin a catheter body. A transducer is attached to the distal end ofthe drive cable. A coaxial cable or transmission line is disposed withinthe drive cable and also couples to the transducer. The coaxial cabledelivers the intermittent electrical transmit pulses to the transducer,and delivers the received electrical radio signals from the transducerto the receiver amplifier. The IVUS catheter is removably coupled to aninterface module, which controls the rotation of the drive cable and thecoaxial cable within the catheter body and contains the transmitter andreceiver circuitry for the transducer. Imaging catheters may alsoinclude a telescoping element, which is used to advance the transducertowards the distal end of the device.

Preventing the drive cable from buckling is important during operationof the IVUS catheter. When the drive cable folds over onto itself in theevent of significant buckling, the electrical connections of the coaxialcable are severed and the imaging catheter is rendered inoperative. Evenin less severe cases, buckling of the drive cable pulls the transducerinward, thereby scanning the incorrect region of the anatomy. Thisbuckling of the drive cable often results from the small but stillexcessive amount of space between the drive cable and various componentsof the imaging device that surround the drive cable. Typically, apolyamide tube is used inside the telescope section of the catheter toconstrain and support the drive cable, especially when the telescope isfully extended. This helps keep the drive cable from buckling when thetelescope is moving forward from the fully extended position. Thepolyamide tube, however, adds unnecessary complexity (increased partnumber) to the device and also adds to assembly costs.

SUMMARY

The present invention provides a telescoping intraluminal imaging devicein which a sheath extends over the telescoping portion of the device inorder to provide increased stabilization and accommodation oftelescoping drive cables.

Devices and methods of the invention reduce buckling of drive cableswithin an intraluminal device by extending a sheath or catheter portionof the imaging device through a telescopic region of the device. Theinvention provides support and contains the drive cable in thetelescoping region. By extending a small-diameter catheter all the waythrough the telescoping element of an intraluminal device, the excessivespace typically associated with drive cable buckling is eliminated.

Devices of the present invention eliminate drive cable buckling withoutthe need for additional components, such as polyimide tubing. As such,devices of the present invention reduce device complexity and are lessexpensive to build. Most importantly, however, the present devicesachieve greater imaging accuracy than conventional telescopic imagingcatheters due to the increased steadiness of the drive cable and itsassociated transducer.

An intravascular device of the invention typically has an elongated bodyconfigured to fit within the lumen of a vessel, a rotatable shaftpositioned inside the elongated body, and a telescoping element. Asencompassed by the invention, a portion of the elongated body extendsthrough the telescoping element and the elongated body is configured tocontain the rotatable shaft inside the telescoping element. The catheterbody extends through the telescope and contains the drive cable evenwhen the telescope is fully extended.

In preferred aspects of the invention, the elongated body is a catheterand a rotatable drive cable is positioned inside the catheter. Theinterior dimensions of the catheter are small enough to prevent bucklingof the drive cable when the drive cable extends through the telescopingelement. For imaging the inside of a vessel, the drive cable may includea working element positioned, in certain aspects, at the distal regionof the drive cable, which facilitates imaging the vessel interior. Incertain aspects of the invention, the working element is a transducer,such as an ultrasonic transducer for use in IVUS. In other aspects ofthe invention, the working element comprises an optical element for usein OCT.

In certain conventional telescoping image catheters, the outer body ofthe catheter, distal of the telescope, contains the drive cable andkeeps it from buckling. As contemplated by the present invention,however, the catheter body is also used to support the drive cable inthe telescope. Accordingly, the need for a separate supportingstructure, such as the polyamide tube is eliminated and the part numberand complexity of the overall device is advantageously reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional side view of a prior art intravascular catheter.

FIG. 2 is another sectional side view of the prior art intravascularcatheter of FIG. 1.

FIG. 3 is a graphical depiction of a device when in a non-extendedposition in accordance with the invention.

FIG. 4 is a graphical depiction of a device when in a extended positionin accordance with the invention.

FIG. 5 is a side view of a device in accordance with the invention.

FIG. 6 is a detail of distal region of the device.

FIG. 7 is a sectional side view of the exemplary device of FIG. 5.

FIG. 8 is a detail of an anchor housing component of the exemplarydevice of FIG. 5.

FIG. 9 is a detail of a catheter coupling component of the exemplardevice of FIG. 5.

DETAILED DESCRIPTION

The invention generally relates to devices that can image an object infront of the device and methods of using those devices. Morespecifically, the invention relates to devices that include an elongatedbody configured for insertion into a lumen of a vessel and at least onesensor located on the elongated body configured to image an object infront of the device. The ability to image an object directly in front ofthe device provides a unique advantage over conventional imagingcatheters that can only image at oblique angles relative to the lengthof the catheter.

The provided device shall now be explained in detail, especially incontrast to conventional imaging catheters. A typical rotational imagingcatheter of the prior art is depicted in FIG. 1. This prior art cathetercomprises a mechanically scanned IVUS catheter which mechanically spinsan ultrasonic beam to sweep across a region of interest in the body. Theprior art device of FIG. 1 mechanically rotates a transducer 46 thatgenerates the ultrasound beam.

Mechanically scanning imaging catheters are formed from a telescopingportion 4 and a catheter body 2. The telescoping portion 4 is operablyassociated with the catheter body 2 to allow an imaging element (such astransducer 46) to translate laterally within the catheter body 2. Thecatheter body 2 is formed from a proximal catheter sheath 27 and adistal catheter sheath 28. The catheter body 2 is the portion of animaging catheter that is positioned within the body for imaging. Thelength of a catheter body 2 is typically in the range from 125 cm to 200cm, which allows the catheter body 2 to extend to various positions deepwithin the vasculature.

The catheter body 2 (sheaths 27 and 28) prevent rotating components 33and 34 from coming into contact with the patient's tissue and causingtrauma. In addition, the sheath provides a lumen 49 through which theimaging element moves along a portion of the distal length of theimaging catheter. Therefore, with a sheathed mechanical scanning IVUScatheter a volume of image data can be acquired over a region ofinterest without physically moving the sheaths 27 and 28 of the catheterwithin the patient's body.

Mechanically scanning IVUS imaging catheters contain drive cables 33 to“spin” the transducer 46 within the catheter body 2 (sheaths 27 and 28).Drive cables are currently assembled by winding multiple strands ofmetal wire on a mandrel to create a long spring containing a repeatingseries of concentric rings, or windings, of the wire. Two or moresprings are wound for each drive cable sized one to fit over the other.Adjacent springs are wound in the opposite direction of each other sothat the grooves between the windings do not line up and lock together.During assembly, the inner spring is inserted into the outer springstill on its winding mandrel and then released so that it expands intothe outer spring. In this way, the drive cable is extremely flexible inorder to navigate small tortuous distal coronary anatomy while stillproviding some degree of torsional rigidity between the proximal drivingend and the distal end containing the transducer.

Proximal housing 25 contains engagement pins 38 that mechanically mateto the imaging system catheter interface port. Within proximal housing25 is a connector 30 which couples in mechanical energy to the drivecable 33 and electrical energy into the transmission line 47 within thedrive cable. Connector 30 is fixedly connected to drive shaft 31, suchthat when rotated by the imaging system, drive shaft 31 is similarlyrotated. Internal drive shaft 31 has a smooth bearing surface 37 whichprovides the running surface for rotational bearing 36 and snap ring 35.Snap ring 35 is fixedly held in place by the groove in proximal housing25. A fluid seal 39 prevents fluids from the lumen 49, which runs thelength of the catheter, from getting into the connector 30. The distalend of internal drive shaft 31 is connected via solder, brazing, weldingor gluing bond joints 32 to the drive cable 33, such that when driveshaft 31 is rotated, drive cable 33 is similarly rotated.

Connector 30 within proximal housing 25 contains an electrical interfaceto couple in rotating electrical energy into the transmission line 47that is disposed within drive cable 33 and runs its entire length.Transmission line 47 couples transmit energy from the system viaconnector 30, through the drive cable 33, and to the transducer 46located within the distal housing 34. The electrical excitation energycauses transducer 46 to generate a pressure wave into the lumen 49 whichis filled with saline via flushing port 40. The ultrasonic energy iscoupled via the saline into the ultrasonically transparent portion ofthe sheath 28 and into the body. Objects in the body having acousticimpedance variations reflect back a portion of the ultrasonic pressurewave which is received by the transducer 46 after passing throughcatheter body 2 and the saline filled lumen 49. Transducer 46 convertsthe received pressure signals into electrical signals which are coupledvia transmission line 47 back to connector 30 and into the imagingsystems' receiver. The system converts a series of scan lines acquiredin the polar (R, θ) coordinate system, (similar to a beam from alighthouse) into a slice or frame of image data by converting the polarscan lines into the Cartesian (X,Y) coordinate system for display on aX-Y scanning monitor, thus completing one rotation of the connector 30,drive shaft 31, drive cable 33, and distal housing 34.

In order to move, or translate, the rotating transducer 46 along thedistal portion of the length of the lumen 49, a telescopic section 4 isadded at the proximal end of the catheter. The telescopic sectioncontains inner proximal tubular element 26, outer distal tubular element50, and anchor housing 29. The outer distal tubular element 50, theanchor housing 29 or both are coupled to the proximal shaft 27 of thecatheter body 2. The inner proximal tubular element 26 and the divecable 33 are coupled to the proximal housing 26. For translation, theouter distal tubular element 50, anchor housing 29, and the catheterbody 2 remain fixed, and the proximal housing is translated in theproximal or distal direction relative to the fixed catheter elements(50, 29, 2). As a result, the drive cable 33 and transducer 46 coupledthereto likewise translates within the catheter body 2. This allows thecatheter body 2 to maintain its location within the body, while therotating imaging transducer 46 is translated within the catheter body 2in order to obtain images along a length of a vessel. The distal end ofinner proximal tubular element 26 contains an end stop 51 to prevent theinner proximal tubular element 26 from disengaging from the outer distaltubular member 50 when the telescope is fully extended. Fluid seal 41,inside anchor housing 29 prevents fluids from lumen 49 from leaking outvia the space between inner proximal tubular element 26 and outer distaltubular element 50. Groove 52 in anchor housing 29 provides a connectionpoint for motorized (controlled) movement of the distal outer tubularelement relative to the proximal housing 25.

Due to the flexible nature of the drive cable 33, the telescope section26, 29, and 50, and catheter sheaths 27 and 28 must provide a runningsurface to support drive cable 33 when it is rotating. It is alsoimportant to note that drive cable 33 is of a fixed length, so that whenthe outer distal tubular element 50 is translated relative to the innerproximal tubular member 26, the transducer 46 is translated relative tothe distal sheath 28. In this way, the transducer 46 is moved along thelength of the sheath 28 to acquire a volume of image data.

Conventional telescoping catheters 1 as exemplified in FIG. 1 haveseveral shortcomings which reduce the effectiveness of the design. Asshown in FIG. 1, the outer distal telescopic tubular member 50 isattached at its proximal end to anchor housing 29 which contains fluidseal 41. Fluid seal 41, applies pressure to inner proximal tubularmember 26. For this reason, inner proximal tubular member 26 must have asmooth outer surface along its entire length in order to form a fluidseal. The distal end of the outer distal tubular member 50 is bonded viaglue 43, to strain relief 44 and the proximal sheath 27 of the catheterbody 2. The inside diameter of the outer distal tubular member 50, issized to accommodate the outside diameter of end stop 51 which must belarger than the outside diameter of the inner proximal tubular member26. Therefore, the inside diameter of the outer distal tubular member 50is larger than the outside diameter of the inner proximal tubular member26. This creates a significant gap between the outside diameter of drivecable 33 compared to the inside diameter of the outer proximal tubularmember 50.

This gap is a major deficiency of the conventional IVUS catheters. Whenthe telescope is fully extended, the transducer is in its most proximallocation within distal sheath 28 of the catheter body. Since the lumen49 is filled with saline, the distal housing 34 and drive cable 33, mustdisplace this fluid as the telescope is retracted and the transducer 46is advanced into the sheath 28. This creates a backward force on drivecable 33. Due to the gap between drive cable 33 and the outer proximaltubular member 50 and the flexible nature of drive cable 33, drive cable33 is compressed into an “S” curve as shown in FIG. 2. This “S” curvepulls the location of transducer 46 inward, thereby scanning theincorrect region of the anatomy and often leads to the drive cable 33folding back over onto itself. When the drive cable 33 folds back overonto itself, the electrical connections of transmission line 47 aresevered and the imaging catheter is rendered inoperative. Approximately1% of all IVUS catheters used are returned as defected units as a resultof this failure mechanism. Certain conventional IVUS catheters, such asthe current REVOLUTION catheter by Volcano Corp., have attempted tomitigate this problem by using a polyimide tube (not shown) inside thetelescope section to constrain and support the drive cable, especiallywhen the telescope is fully extended. This helps keep the drive cablefrom buckling when the telescope is moving forward from the fullyextended position. The polyamide tube, however, adds unnecessarycomplexity (increased part number) to the device and also adds toassembly costs.

As will be become evident from the following description and providedfigures, the embodiments of the present invention shown in FIGS. 3-9include improvements to the catheter portion of the device, whicheliminate buckling of the drive cable without the additional complexityand cost of the polyamide tube.

In conventional rotational imaging catheters, the catheter body 106 doesnot extend all the way through the telescoping element, hence creatinggaps (shown as 6 in FIGS. 1 and 2) between the outer surfaces and thedrive cable, which can lead to buckling. In other conventional devices,the catheter body still does not extend all the way through thetelescoping portion, but a separate tubular element (e.g., a polyamidetube) is used to support the drive shaft in the gap 6 in order tocompensate for the gap effect and support the drive cable.

The present invention solves the above-described problems associatedwith the gap 6 of prior art devices by extending the catheter body 106into the telescoping portion 4 (as shown in FIGS. 3-7). Because thecatheter body 106 into the telescoping portion 4, the catheter body 106acts to protect and provide extra support to the drive cable 110 whendisposed within the telescoping portion 4. That is, the shaft of thecatheter body 106 fills the gap 6 present in prior art catheters andeliminates/reduces proximal buckling of the drive cable in thetelescoping portion as seen in the prior art catheter of FIGS. 1 and 2.The components and mechanics of the catheter 100 of the invention aredescribed in more detail hereinafter.

As best seen in FIGS. 3 and 4, the catheter includes a catheter body 106(formed from a first portion 4 and a second portion 5) and a telescopingportion 4. The telescoping portion 4 is operably associated with aproximal housing 109 that includes a rotary unit with a drive shaft. Theproximal housing 109 is able translate relative to the catheter body 106(as shown by arrow X in FIG. 4) while providing rotation to a drivecable 110 via the drive shaft. The proximal housing 109 can betranslated manually or be coupled to a system (such a pullback device)that facilitates the movement of the proximal housing 109 and rotationof the drive shaft within the proximal housing 109. The drive cable 110carries at its distal end a working element. In certain embodiments, theworking element is an imaging transducer 111. As may be appreciated, theworking element could alternatively be an optical minor or an opticallens, depending on the intended use of the catheter. If the workingelement is an optical element such as a minor or lens, the transmissionline of the device would then be replaced by an optical fiber, forexample. When the drive cable 110 is rotated and translated within thecatheter body 106, the imaging transducer 111 is able to obtaincross-sectional and tomographic images along a length of a body lumen(such as a blood vessel).

The catheter body 106 includes a first portion 5 and a second portion 3.The second portion 5 is a portion of the catheter body 106 that is notdisposed within the telescoping section 4. The second portion 5 of thecatheter system may range from 125 cm to 200 cm, and the portion of thecatheter body 106 that is introduced into the a patient's body. Thesecond portion 5 of the catheter body 106, thus mirrors the cathetershafts 27 and 28 of the prior art catheters. However, instead of thecatheter body 106 terminating at the second portion 5 like prior artcatheters, the catheter body 106 in devices of the invention extendsinto the telescoping section 4. The first portion 3 of the catheter body106 is the portion that extends into the telescoping portion 4 of thecatheter 100. Thus, the catheter body 106 extends over the drive cable110 within the telescoping portion 4 such that the catheter body 106fills the gap 6 (of prior art catheters (FIGS. 1 and 2) and providesadditional support to the drive cable 110. The catheter body 106 can beformed from a single material or multiple materials. In addition, thecatheter body 106 may be segmented (e.g. of variable flexibility alongits length). For example, the first portion 3 of the catheter 106 withinthe telescoping may be stiffer than the second portion 5 of the catheterbody 106. In addition, the second portion 5 of the catheter body 106 mayhave a stiff proximal section and a more flexible distal section.Catheters bodies with variable thickness are described in more detail inU.S. Publication No. 2009/0018393.

The telescoping section 4 contains distal outer tubular member 105, aninner proximal tubular member 102 that slides into the distal outertubular member 105, and an anchor housing unit 104 with an optionalfluid seal 103 (in FIGS. 5 and 6). Although tubular members 102 and 105are described as tubular, it is understood that these members can haveother shapes. The outer distal tubular member may be coupled to thecatheter body 106 via catheter coupling 107. The anchor housing unit 104is coupled to the distal outer tubular member 105 and the catheter body106. The anchor housing unit 104 can be held, either manually or by asystem (such as pullback device), in a fixed position, thereby alsomaintaining the positioning of the distal outer tubular member 105 andthe catheter body 106. The inner proximal tubular member 102 and thedrive cable 110 is operably associated with the proximal housing suchthat translation of the proximal housing 109 causes the inner proximaltubular member 102 and the drive cable 110 to likewise translate. Theproximal housing 109 can likewise be associated with the system (such asa pullback device) that causes the proximal housing and the innerproximal tubular member 102 and drive cable 102 to translate. The drivecable 110 is coupled to a rotary drive shaft of the proximal housing 109which causes the drive cable 110 to rotate as well. The system inaddition to translating the drive cable may be configured to providerotation to the rotary drive shaft.

It is important to note that drive cable 110 is of a fixed length, sothat when the inner tubular member 102 of the telescope section 4 istranslated relative to the outer tubular member 105 and catheter body106, the transducer 111 is translated relative to the catheter body 106

Each of the distal outer tubular member 105, inner proximal tubularmember 102, anchor housing unit 104, and catheter body 106 define alumen to receive the drive cable 110 therethrough. In addition to drivecable 110, the lumen of the distal outer tubular member 105 isconfigured to receive the inner tubular member 102 and the catheter body106. The lumen of inner proximal tubular member 102 is configured toreceive the catheter body 106 and the drive cable 110. That is, thelumen of the inner proximal tubular member 102 is sized to fit the outerdiameter of the proximal section 3 of the catheter body 106. Theseconfigurations allow the inner proximal tubular member 102 and the drivecable 110 to slideably translate (as shown by x in FIG. 4) relative toouter distal tubular member 105 and catheter body 106.

FIGS. 3 and 4 illustrate translation of the telescoping portion 104during an imaging pullback. An imaging pullback is the translation ofthe imaging transducer along a length of the catheter body. During theimaging pullback, the imaging transducer is able to obtain images alonga length of the vessel in which the catheter is disposed. When rotatedand translated, the imaging transducer is able to obtain cross-sectionaland tomographical images of the vessel.

FIG. 3 illustrates the catheter 100 in a fully non-extended position. Ina fully non-extended position, the distal outer tubular member 105, theinner proximal tubular member 102, and the proximal section 3 of thecatheter body 106 are substantially concentrically aligned. When in thefully non-extended position, the imaging transducer 111 at a distal endof the drive cable 110 is at the distal end of the catheter body 106.Typically, imaging is initiated when the imaging transducer 111 is atthe distal end of the catheter body 106, and then imaging transducer ispulled back (proximally) within the catheter body to image along alength of the catheter body. In order to initiate the pullback imaging,the telescoping section 4 transitions from a non-extended position to anextended position. In order to transition into an extended position, theinner proximal member 102 and drive cable 110 are moved in the proximaldirection relative to the catheter body 106 and outer distal tubularmember 105. FIG. 4 illustrates the catheter 100 in a fully extendedposition. As shown in FIG. 4, the inner proximal tubular member 4, drivecable 111, and proximal housing 109 moved a length L in the distaldirection. At the same time, the distal outer tubular member 105, theanchor housing 105 and the catheter body 106 maintain their position.This causes the imaging transducer 111 coupled to drive cable 110 tolikewise translate a distance L within the catheter body 106.

As an alternative to pullback imaging, the catheter of the invention isalso configured to image using a push-forward. For this imaging, thetelescoping portion 4 of the catheter 100 transitions from an extendedposition to a non-extended position.

In certain embodiments and as shown in FIG. 4, the inner proximaltubular member 102 may include stoppers 133 that act to stop theproximal translation of the inner proximal tubular member 102 at acertain point. For example, the stoppers 133 can be configured toprevent the inner proximal tubular member 102 from exiting a proximalend of the anchor housing 104.

The drive cable 110, is generally the same as drive cables associatedwith devices of the prior art. In contrast to the prior art devices,however, the catheter sheath 106 surrounding the drive cable 110 extendsall the way back through the telescope portion 4 of the device,containing the drive cable 110 even when the telescope portion 4 isfully extended (i.e. when the distal outer tubular element 105 of thetelescoping portion is fully extended over the catheter body 106).

FIG. 5 illustrates an additional view of a catheter of the inventionwhen the telescoping region 4 is in an extended position. As shown inFIG. 5, the catheter includes a telescoping section 4 (with outer distaltubular member 105, inner proximal tubular member 102, and anchorhousing 104 with fluid seal 103) and a catheter body 106 (first portion3 and section portion 5). The first portion 3 of the catheter body 106is disposed within the telescoping portion 4 to provide more support tothe drive cable 111(which is positioned within the telescoping portion 4and catheter body 106). As further shown in FIG. 5, the inner proximaltubular member 102 is coupled to proximal housing 109.

In certain embodiments, the proximal housing 109 may contain containsengagement pins that mechanically mate to the imaging system catheterinterface port. A connector 113 may be position that provides mechanicalenergy to the drive cable 110 and electrical energy into a transmissionline within the drive cable. Connector 113 is fixedly connected to driveshaft 114, such that when rotated by the imaging system, drive shaft 114is similarly rotated. Internal drive shaft 114 may have a smooth bearingsurface which provides the running surface for a rotational bearing andsnap ring. The snap ring may be fixedly held in place by the groove inproximal housing 109. A fluid seal 103 prevents fluids from the lumen117, which runs the length of the catheter 100, from getting into theconnector 113. The distal end of drive shaft 114 may be connected viasolder, brazing, welding or gluing bond joints to the drive shaft 114,such that when drive shaft 114 is rotated, drive cable 110 is similarlyrotated.

Connector 113 within proximal housing 109 contains an electricalinterface to couple in rotating electrical energy into the transmissionline disposed within drive cable 110 and runs its entire length. Thetransmission line couples transmit energy from the system via connector113, through the drive cable 110, and to the transducer located at theend of the drive cable 110. The electrical excitation energy causes thetransducer to generate a pressure wave into the catheter 100 which isfilled with saline via flushing port 101. The ultrasonic energygenerated by the transducer 111 sends acoustic signals through thesaline and the sheath to the biological or non-biological objects in abody lumen (e.g. vessel tissue, plaque, thombus, blood) and thetransducers receives returns signals of those objects. Objects in thebody having acoustic impedance variations reflect back a portion of theultrasonic pressure wave which is received by the transducer 111 afterpassing through catheter body 106 and the saline filled catheter body106. The transducer 111 converts the received pressure signals intoelectrical signals which are coupled via transmission line back toconnector 113 and into the imaging systems' receiver. The systemconverts a series of scan lines acquired in the polar (R, θ) coordinatesystem, (similar to a beam from a lighthouse) into a slice or frame ofimage data by converting the polar scan lines into the Cartesian (X,Y)coordinate system for display on a X-Y scanning monitor, thus completingone rotation of the connector 113, drive shaft 114, drive cable 110, andtransducer 111.

FIG. 7 illustrates a cross-sectional view of the catheter depicted inFIG. 5 (that is in an extended position). In order to move, ortranslate, the rotating transducer 111 along the distal portion of thelength of the catheter body 106, a telescopic section 4 is added to thecatheter 100. The telescopic section 4 contains distal outer tubularmember 105, a proximal inner tubular member 102 that slides into thedistal outer tubular member 105 and an anchor housing unit 104 with afluid seal 103. In certain embodiment, the proximal end of the proximalinner tubular member 102 contains an end stop (such as stoppers 33) toprevent the proximal inner tubular member 102 from disengaging the outertubular member 105 when the telescope section 4 is fully extended. Fluidseal 103 is located inside the anchor housing 104 and prevents fluidsfor priming the catheter body 106 from leaking out via the space betweendistal outer tubular member 105 and the proximal inner tubular member102. The device 100 may also, in certain embodiments, encompass a strainrelief component that contains a groove which provides a connectionpoint for motorized (controlled) movement of the telescoping element 4.As shown in FIG. 6, the catheter body 106 passes through a cathetercoupling 107 distal to the anchor housing 104. In certain embodiments,the catheter body includes one or more holes 108 within the catheterbody 106 to help purge air out of the catheter body during the primingprocess.

FIG. 8 provides a close-up view of section E in FIG. 7. Section Ehighlights the overlapping telescoping section 4 at the location of theanchor housing 104. As shown in FIG. 8, the catheter body 106 isdisposed within and co-axially aligned with portions of the outer distaltubular member 105 and the inner proximal tubular member 102. The innerproximal tubular member 102 and drive cable 111 translates relative tothe catheter body 106 and the outer distal tubular body 105 when thetelescoping section 4 transitions from the extended position to anon-extended position. As a result, the imaging transducer 111 islikewise translated within a distal portion of the catheter body 106.

As mentioned above, the catheter 100 of the encompassed device not onlysupports the distal portion of the drive cable 110 as in conventionalIVUS catheters, the provided catheter also supports the drive cable 110inside the telescope section 104, preventing potential buckling byeliminating the gap between the inner surfaces of the telescopecomponents and the drive cable. Moreover, the encompassed deviceeliminates the need for a separate polyamide tube, thus reducing devicecomplexity and overall cost. The extension of the catheter throughoutthe device and telescope components is particularly evident in FIGS. 3and 4, which illustrates the catheter in the extended and non-extendedpositions.

In certain embodiments, the components comprising the telescopingsection 4 and the catheter body 106 are prepared from biocompatiblematerials, which are well-known in the art. Catheter bodies and/ortelescoping components will typically be composed of an organic polymerthat is fabricated by conventional extrusion techniques. Suitablepolymers include polyvinylchloride, polyurethanes, polyesters,polytetrafluoroethylenes (PTFE), silicone rubbers, natural rubbers, andthe like. Optionally, the catheter body may be reinforced with braid,helical wires, coils, axial filaments, or the like, in order to increaserotational strength, column strength, toughness, pushability, and thelike. Suitable catheter bodies may be formed by extrusion, with one ormore channels being provided when desired. The catheter diameter can bemodified by heat expansion and shrinkage using conventional techniques.The resulting catheters will thus be suitable for introduction to thevascular system, often the coronary arteries, by conventionaltechniques. Preferably, at least a portion of the catheter body isflexible.

According to certain aspects, the proximal housing 109 and/or anchorhousing 104 may be operably associated with a system that operates totransition the catheter between the extended and non-extended positions.Such a system is commonly referred to as a pullback device or patientinterface module (PIM) for rotational catheters. The pullback device canperform several functions such as providing the translation and rotationof the catheter components as needed to obtain an image along a lengthof a body lumen. In addition, the pullback system can be configured toprovide the necessary energy to the imaging element located on thedistal end of the drive cable. The energy provided can be optical (e.g.for optical coherence tomography imaging elements) or electrical (e.g.for ultrasonic imaging elements). Patient interface modules are known inthe art, and are described in, for example, U.S. Publication No.2003/0187369 and U.S. 2013/0223798. A suitable pullback device for usewith methods of the invention is the SPINVISION Pullback device fromVolcano Corporation. When using pullback devices, the proximal housing109 can be configured to mate or connect with the pullback device beingused.

While particular embodiments of the present invention have been shownand described, modifications may be made, and it is therefore intendedto cover in the appended claims, all such changes and modificationswhich fall within the true spirit and scope of the invention as definedby those claims.

INCORPORATION BY REFERENCE

References and citations to other documents, such as patents, patentapplications, patent publications, journals, books, papers, webcontents, have been made throughout this disclosure. All such documentsare hereby incorporated herein by reference in their entirety for allpurposes.

EQUIVALENTS

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The foregoingembodiments are therefore to be considered in all respects illustrativerather than limiting on the invention described herein. Scope of theinvention is thus indicated by the appended claims rather than by theforegoing description, and all changes which come within the meaning andrange of equivalency of the claims are therefore intended to be embracedtherein.

What is claimed is:
 1. A device for imaging the interior of a vessel,the device comprising: an elongated body configured to fit within thelumen of a vessel; a rotatable shaft positioned inside the elongatedbody; and a telescoping element; wherein a portion of the elongated bodyextends through the telescoping element; and wherein the elongated bodyis configured to contain the rotatable shaft inside the telescopingelement.
 2. The device of claim 1, wherein the elongated body comprisesa catheter.
 3. The device of claim 2, wherein the telescoping elementcomprises an outer tubular member and an inner tubular member.
 4. Thedevice of claim 3, wherein a portion of the catheter extends through theinner tubular member.
 5. The device of claim 4, wherein the rotatableshaft comprises a drive cable.
 6. The device of claim 1, furthercomprising a working element positioned at a distal region of therotatable shaft.
 7. The device of claim 6, wherein the working elementcomprises a transducer.
 8. The device of claim 7, wherein the transducercomprises an ultrasound transducer.
 9. The device of claim 6, whereinthe working element comprises an optical element.
 10. The device ofclaim 1, wherein the catheter comprises a plurality of holes.
 11. Thedevice of claim 5, wherein the telescoping element comprises an extendedconfiguration and a non-extended configuration, and the catheter isconfigured to contain the drive cable when the telescoping elementcomprises the extended configuration.